更新到5.1.0后将数据发布到WebApi失败

I have an web app that use webapi for loading / saving data All used to work ok/ Today I found that there is an updated to ASP.NET MVC / webapi, and I installed the update But after that POSTing data with jquery no longer works. I made no change either in client code or in webapi controller.I have an web app that use webapi for loading /